1. Field of the Invention
The present invention is related to information handling systems, and more specifically, to embedded control and monitoring of hard disk drives in the information handling systems.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes, thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems, e.g., computer, personal computer workstation, portable computer, computer server, print server, network router, network hub, network switch, storage area network disk array, RAID disk system and telecommunications switch.
Hot-swap SCSI disk drives may be used in RAID disk systems. These hot-swap SCSI disk drives are housed in a matching drive chassis or cage having a SCSI backplane (bus) which includes a SAF-TE (SCSI Accessed Fault Tolerant Enclosure) logic that provides an interface to the SCSI disk drives for the support of status signals, hot swapping drives, and enclosure monitoring. The SAF-TE protocol is an industry standard that allows the SCSI bus to be used for control and status purposes.
The SAF-TE interface provides this industry standard, non-proprietary way for third party disk and RAID controllers to be automatically integrated with peripheral packaging that supports status signals (LEDs, audible alarm, LCD, etc.), hot swapping of hard drives, and monitoring of enclosure components. From the system vendor's point of view, this allows quick integration of the best third party controllers, knowing that they will fully integrate with disk and peripheral packaging. It also allows a selected controller to work with a variety of expansion packaging, being fully able to sense status and drive enclosure indicators. The cost of a separate cable and interface for enclosure services is also eliminated.
SCSI is the underlying transport mechanism chosen for communicating enclosure information. This means that all standard SCSI host adapters will work. No special considerations, such as reserved signals on the SCSI bus, or additional cables are required. The SAF-TE Interface is implemented using a simple SCSI part and a microcontroller. The SAF-TE processor (SEP) device conforms to the ANSI SCSI-2 specification for processor devices.
The SAF-TE processor has two interfaces, SCSI and I2C. The SAF-TE processor performs the SAF-TE target protocol entirely with its SCSI interface. A RAID on motherboard (ROMB) controller communicates with the SAF-TE processor to perform a number of operations. Since the SAF-TE processor is located on the SCSI backplane (bus), it also performs a number of embedded management functions, e.g., monitoring temperatures, voltage and fans, and reports that information to an Embedded Server Management (ESM) system via the I2C interface.
When the SCSI backplane (bus) is split into two buses, for added speed, redundancy, etc., a second SAF-TE processor, commonly located on a SCSI daughtercard, must be added to the system backplane. Split SCSI backplane configurations separate the hard drives such that two separate SCSI channels may independently control the hard drives. However, since the SAF-TE protocol must be run on each SCSI bus, a separate SAF-TE processor is needed for each bus. Thus, the SCSI daughtercard serves this purpose in combination with the standard SAF-TE processor on the SCSI backplane.
The cost of a SAF-TE processor on the SCSI backplane is not trivial. The SAF-TE processor also occupies backplane board space and restricts airflow ventilation through the SCSI backplane. Since the information handling systems are becoming more dense and total power consumption increases, any improvements in reducing power consumption, increasing airflow ventilation and/or reducing costs are very beneficial.